Items of technical equipment are generally bought for their functionality. They are quickly superseded and replaced when a faster, cheaper to operate, smaller, or higher specification alternative is released onto the market, the previous model being discarded. The value of the product to its user is in what it can achieve, and perhaps to an extent the image that attaches to the owner of such an item. As fashion is constantly changing so is the image promoted by owning an individual item particularly in a fast moving technical area. What may have been the height of fashion can swiftly become out moded.
In fast moving technical areas changes are prompted by, amongst other things, the requirement to make the product smaller, cheaper, cheaper to use, have greater functionality, make use of emerging technologies or move with the latest tastes in design.
Generally when a radically new technical product is brought onto the market, for an initial period the product is elite and expensive. Consequently only limited numbers are produced. In the early years, because of the inherent rarity and the cost of components, there is a propensity to repair as much as possible. Despite the economic requirement for repair, as soon as a better product is launched, the previous item is soon obsolete and abandoned. The drive for innovation is the challenge of technical advancement and reduction of costs. This pattern has been followed with many items including the first colour televisions, and the first mobile phones.
In other products such as personal computers upgrading is a possibility, but these upgrades are possible only within carefully predefined limits. The casings being retained as a matter of convenience, it being the retention of the maximum amount of the existing technological hardware that drives the changes.